Vacuum equilibrium flash vaporization equipment



ug- 23, 1960 c. J. RYANT, JR., Erm. 2,949,768

VACUUM EQUILIBRIUM FLASH VAPORIZATION EQUIPMENT Filed May 7, 1957 3Sheets-Sheet 1 Aug- 23, 1950 c. J. RYANT, JR., ETAL 2,949,768

VACUUM EQUILIBRIUM FLASH VAPORIZATION EQUIPMENT Filed May '7, 1957 3Sheets-Sheet 2 Feed Drain L35 F ig. 2

INVENTORS Char/es J. Ryanf, Jr. Sixt Frederick Kapff BY fum'ay.

3 Sheets-Sheet 3 C. J. RYANT, JR., ETAL Aug. 23, 1960 VACUUM EQUILIBRIUMFLASH'VAPORIZATION EQUIPMENT Filed May 7, 1957 5258. ENE mms.; izmmrta@K v mv INVENTORS:

ATTWEV .m JM um on H Q. J. d L a F w n m w Vl a 546528 mwwm mi nitedStates Patent ffice e Patented Aug. 23, 1960 VACUUM EQUILIBRIUM FLASHVAPORIZATION EQUIPMENT Charles J. Ryant, Jr., Chicago, and SixtFrederick Kapfi, Homewood, Ill., assignors to Standard Oil Company,Chicago, 111., a corporation of Indiana Filed May 7, 1957, Ser. No.657,589

9 Claims. (Cl. 'I3- 53) This invention relates to the problem ofestablishing the phase diagram for a petroleum fraction. Moreparticularly, the invention relates to a system for determining thephase diagrams of petroleum fractions in order to predict temperatureprofiles for furnaces as well as to establish the requisite furnaceduty.

Among the more important data required in the design of petroleumrefinery equipment are the phase conditions of the Ipetroleum fractions.In spite of its importance and frequent occurrence in the design ofpetroleum refinery equipment, the prediction of the phase condition forpetroleum stocks has received very little experimental attention. Moreparticularly, `data on heavy stocks has been very meager inasmuch -asequilibrium liash vaporiza- `tion of such heavy stocks should beobtained under subatmospheric pressures in order .to lower thetemperatures .and eliminate cracking.

Interest in low pressure ashing of high boiling residua has introduced aneed for reliable vapor pressure data for high boiling hydrocarbons andhas promoted `development of methods which enable the designer toestimate the quantity of materials that will be vaporized in a :dashingchamber.

The known methods inestimating flash vaporization, include, for example,that described in an article entitled Phase Relations and PetroleumFractions, by Edmister and Pollock, Chemical Engineering Progress,volume 44 (1948), page 905, which is a basis for `an empirical methodfor predicting equilibrium diash vaporization conditions of low boilinghydrocarbons. However, low pres- 'sure extrapolation of the correlationshave not been practical since some attempted correlations differ Widelyin the high boiling temperature range.

Heretofore, the following timeconsuming procedure has been used inconstructing a phase diagram:

(l) Determine .the API gravity.

(2) Run -an atmospheric ASTM distillation until cracking begins. Forreduced crudes this generally occurs before the 30% vaporization point.

-(3) Run `a l0 mm. vacuum distillation.

(4) `Correct the 10 mm. vacuum distillation by an empirical curve tosome unknown pressure so that the corrected -vacuum distillation curvewill agree with the incomplete curve of the atmospheric ASTMdistillation.

(5) Extrapolate the derived ,atmospheric ATSM distillation so it willindicate a temperature at which 90% of the original charge would bevaporized in an atmospheric ASTM distillation.

y( 6) From an empirical correlation involving the ASTM 50% point and theASTM 10% to 30% slope of the atmospheric ASTM distillation curve,determine the atmospheric equilibrium flash vaporization (E.F.V.) 50%point.

(7) From an empirical correlation involving the ASTM slopes, determinethe E.F.V. slopes.

(8) Knowing the 50% E.F.V. point and the E.F.V. slopes, draw anatmospheric E.F.V. curve.

(9) From an empirical correlation involving the ASTM volumetric averageboiling point and the API gravity of the substance, determine thecritical temperature for the petroleum fraction.

From `an empirical correlation involving the ASTM 10% to 90% slope, theASTM volumetric average boiling point, `and the API gravity of thesubstance, Idetermine the critical pressure for the petroleum fraction.

(l1) From `an empirical correlation involving the ASTM 10% to 90% slope,the ASTM volumetric average boiling point, and the critical temperature,determine the focal temperature for the petroleum fraction.

(l2) From .an empirical correlation involving the ASTM 10% to 90% slope,the ASTM volumetric average boiling point, and the critical pressure,determine the focal pressure for the petroleum fraction.

(13) `On coordinate paper of log of absolute pressure verus thereciprocal of the quantity of temperature in F. plus 382, plot theatmospheric E.F.V. (10% pt., 20%, 30%, etc.) and the focal point (focaltemperature and focal pressure). Draw straight lines between theatmospheric E.F.V. points and the focal point. These straight lines arelines of constant vaporizations.

Thus, the need for an inexpensive, accurate and rapid system fordetermining the equilibrium ilash vaporization of petroleum fractions isevident. However, de vices and systems heretofore proposed required avery large sample, were not easily controlled, could not be readilyoperated at atmospheric pressure or sub-atmospheric pressure andinvolved time-consurning operations under the supervision of highlytrained technical personnel. Thus, the systems were not adaptable forroutine use on micro samples and have not been generally adopted.

It is, therefore, a primary object of our invention to provide a systemwhich is simple in operation and adapted for routine determinations bynon-professional personnel. A further object "of the invention is toprovide an apparatus which requires a minimum volume of sample. Anotherobject of the invention is to provide a system Vwhich may be operatedover wide pressure ranges and which is easily controlled. Still anotherobject of the invention is to provide an apparatus and method `fordetermination of equilibrium -ash vaporiz-ations which is well suitedfor quality control by plant technical service groups in refineries andin acceptance performance testing of processing units charging andproducing high boiling hydrocarbon mixtures. These `and other objects ofthe invention will become apparent as our description thereof proceeds.

Briey, according to our invention, we provide a systern for constructinga phase `diagram :by obtaining the equilibrium flash -vaporizationdirectly and using one empirical correlation for `deterrninating thefocal point. When the equilibrium ilash vaporization curve is obtainedyat two pressures, there is no need for determining the yfocal point perse.

Our system employs the principle of measuring the portion of the chargeIthat is not vaporized, in contratdistinction to other systems whereinthe vaporized portion was condensed to determine the amount ofvaporization. An important feature of our equilibrium flash vaporizationequipment is a downflow liquid vaporizer which avoids difficultiesheretofore encountered in controlling back pressure. In earlier systemsthere is a tendency for the fluid to slug 'due to the fact that pressuremust build up within the vaporizer to force the fluid out of thereboiler. Such operation results in erratic conditions and causes a dropin temperaure as a result of the additional self-cooling due to flashingof the charge which is caused by sudden decrease in the pressure whenthe slug is released.

Our apparatus comprises a downow vaporizer chamber having ar pluralityof parallel ow channels, means for controlling the temperature of thevaporizer chamber, a feeding device for supplying the sample at a doniteconstantrate, an equilibrium chamber in which the vapor produced iscontacted with liquid containing the same components, separate means forremoving vapors and unvaporized portion, and means for accumulating andtiming the accumulation of a selected standard volume of unvaporizedsample under preselected temperature and pressure conditions.

The downtlow equilibrium flash Vaporizer is provided with controllableelectrical cartridge heaters, thermocouple means and pressure gaugemeans. The inlet portion of the vaporizcr is also provided with a watercooling coil or jacket to assist in the temperature control of the unit.

Further details of the construction and advantages of our system will bedescribed by reference to preferred embodiments thereof illustrated inthe accompanying drawings wherein:

Figure l is a schematic diagram of the equipment;

Figure 2 is a vertical section of the vaporizer unit in Figure l;

Figure 3 is a section taken along the line 3-3 ini Figure 2;

Figure 4 is a bottom view taken along the line 4-4 in Figure 2; and

Figure 5 is a schematic and circuit diagram illustrating a continuousand automatic embodiment of the apparatus.

Referring to the drawings, feed enters the top of the block vaporizer lothrough por-t 11 and impinges upon the deflector plate 12 supportedwithin the manifold section 13 above the heat exchanger section 14 inthe vaporizer 1t). The feed passes down through the many parallelchannels 15 in the heat exchanger section 14 into the bottom separatorchamber 16 after passing through the perforated metal cones 17, 18 and19 in the disengager section 20 immediately below the heat exchangersection 14 and above the separator chamber l16A. The unvaporized liquidleaves the separator chamber 16 by overflowing a circular weir 21 formedby the outlet line 22 in the concave end plate 23 forming the bottomwall of the separator chamber 16. The vapor passes out through arelatively large diameter take-olf conduit 24 communicating with thedisengager section 20 between perforated cones 17 and 18. The Withdrawnvapor may be condensed by passing through condenser 25 and the fluidspassed to the series surge drums 26 and 27, provided with drains 28 and29. A vacuum pump 30 takes suction on drum 27.

A plurality of electrical heating elements or cartridges 31, disposedwithin cylindrical recesses or chambers 32 in the walls of the vaporizer10, may be separately controllable to rapidly attain equilibrium ofvapor and liquid. Temperature and equilibrium are indicated by athermocouple 33 maintained in the liquid phase of the separator chamber16. For a given temperature, the degree of vaporization is obtained bycalculation from the length of time for the receiver or accumlator 35 tobe filled as sensed by the differential thermocouple 34.

The volumetric receiver or accumulator 35 is mounted between a pair ofconduits including bellows 36 and 37, the upper conduit receiving theliquid from the separator chamber 16 in the vaporizer 1t) and the lowerconduit 37 being controlled by normally open solenoid valve 38. When ontest, the valve 3S is closed after equilibrium temperature is attainedin disengager section 20 and remains closed until the diierentialthermocouple 34 in the ask 35 indicates that the desired level of liquidhas accumulated therein. Simultaneously, the length of time foraccumulating this standard volume of unvaporized liquid allioliillyindicated by timer 39 and the valve 38 is opened for discharge of thecollected volume of liquid.

Suitable means can be provided for controlling the temperature of thevaporizer 10 and this may include the cartridge heaters 31 as well as asupplementary cooling coil or jacket 40 surrounding the manifold chamber13 and a portion of the heat exchanger 14 in the vaporizer 10. Othercontrols and recorders are well known in the art and may be applied toour system to make it fully automatic. We may, for example, provide forrepeated tests at the same temperature and different pressure; likewise,we may electrically determine the ratio of the times for collecting thestandard volume of liquid under the selected temperature and pressureconditions.

To operate our equilibrium flash vaporizer apparatus, we perform thefollowing steps:

(l) The constant volume ow into the vaporizer unit 10 is established;

(2) The desired flashing pressure is provided by vacuum pump 30;

(3) The temperature of the vaporizer 10 is adjusted by control of theelectrical cartridge heater 31 so that it is only about 1 degree higherthan the desired ashing temperature;

(4) The time necessary to accumulate the standard volume of unvaporizedcharge in ilasl; 35 at the established temperature and pressure of thevaporizer 10 is determined;

(5) Step 4 is repeated at the same temperature, but at a pressure wherethere will be no vaporization;

(6) Ratio of the times obtained in steps 4 and 5 gives the volumepercent of the original charge which is not vaporized at a giventemperature and pressure; and

(7) Steps 4 and 5 are repeated at a series of temperatures to obtainsufficient points to establish the entire flash curve.

A complete set of points for an E.F.V. curve can be established rapidlyand even heavy stocks can be run under reduced pressures through thevertical downow vaporizer 10. Feed enters the top of the vaporizer 10supplied at a constant rate by pump 41 from feed tank 42 and passesdownwardly through parallel channels 15 in the body of the vaporizeri1t). A solid deflector plate 12 above the exchanger section 14 assuresuniform distribution of liquid feed to the parallel exchanger channels15. Perforated metal cones 17, 18 and 19 disposed immediately below theexchanger section 14 mix the liquid and vapor coming out of the parallelchannels 15. The deflector plate 12 and the perforated metal cones 17eliminate any sensitivity to feed rate variations thus assuringuniformity and reproducibility of data.

The downflow liquid v-aporizer 10 employed in our system isself-draining and is designed with a ratio of heat transfer surface tocross-sectional lflow area which insures that all the charge willvaporize at a given temperature and pressure by the time it reaches theoutlet of the vaporizer. Thus we achieve virtually instantaneousequilibrium and the apparatus is designed so that the force of gravityon the liquid is suicient to separate liquid from vapor without theexistence of a pres sure differential. lln addition, we provide aplurality of flow paths 15 so that the pressure of the duid at the inlet11 of tlhe vaporizer '-10 is equal to the pressure at which the outletof the liquid-vapor separator 16 is being operated.

To operate the equipment illustrated in Figure 5, the control button 43is depressed to start the pump 41, to supply current to the heaters 31in the E.F.V. equipment 1i), and to start the vacuum pump 3i). Apressure controller 45, which is connected to the E.F.V. equipment 10 byline 46, is set for some selected initial pressure of about l0 mm.mercury. A temperatur-e controller 47 is set for some selected initialtemperature of about 300 F. and the therrnocouple 33 in the E.F.V.equipment 10 is used to indicate the temperature and to govern 'theamare@ temperature controller 47. llhe timer 48 is act-uated when thetemperature controller 47 reaches the selected initial temperature. Ifthe temperature within the E.F.V. equipment 10, as sensed by thethermocouple 33, has been maintained at about i0.5 -F. for a period ofapproximately l minutes, then the valve 3S will close.

When the valve 38 closes, it actuates the second timer 39 and causes theliquid to rise Within the collection bulb 35. The bulb 35 is providedwith a level sensing means, 'such as differential temperaturethermocouple 34. Other level detectors and telemetering means well knownin the art may be used. However, in the illustrated embodiment, whenthere is a decrease in the differential temperature, the second timer3-9 is stopped and the valve 38 is automatically opened to permit the owof liquid from the bulb 35. The total liquid flow being pumped by pump41 then ows through the E.F.V. equipment and down the drain 49.

When the second timer `39 is stopped, the elapsed interval will indicatethe length of time required to accumulate within the bulb 35 thestandard volume of liquid. Simultaneously the pressure controller 45communicating with the E.F.V. equipment 10 is reset to either a high orlow pressure las the case may be, and then the cycle is repeated.

When the second timer 39 stops, two events occur alternately; rst thepressure controller 45 will be reset to either a high or a low pressure,as the case may be. In other words, if the E.F.V. equipment 10 wasoperating at about l() mm. of pressure and the second timer 39 isstopped, then the pressure control 45 resets the pressure to anotherpredetermined pressure and the cycle is repeated. When the Second timer39 stops, it also causes the temperature control reset 50 to advance thetemperature controller 47, for example, about l0, and begin the completecycle again. The pressure in the E.F.V. equipment 10 is controlled byproviding a pressure connection 46 between the equipment 10 to apressure controller 45 which in turn actuates a valve 51 which bleedsair into the suction line 52 of the vacuum pump 3b. tln other words,constant pressure is maintained by running the vacuum pump 30 steadilyand by controlling the air bleed 53.

High pressures as used herein is that pressure where there is novaporization at a given temperature and low pressure is here consideredas of the order of l0 mm. of pressure.

Second timer 39 also is a recorder and may be provided with a computingcircuit which permits the plotting of a ilash curve as the results arereceived. The curve is plotted on van X--Y recorder rather than acircular chart Where the temperature is along one axis and the ratio ofthe time intervals (which is actually a volume percent not vaporized)along the other axis.

The second timer may be provided with a program cam or other apparatusincorporated in it which permits any number of determinations to be madeat a given temperature or pressure, as the case may be.

If the operator desires to have a high and a low pressure comparison, weprovide a selective switch which would automatically initiate a test ata different temperature. Thus we may provide 'a control switch meansassociated with the second timer 39 which is capable of repeating aiirst event following which a second event is initiated when theprescribed number of occurrences of the first event has been reached.

Although we have described the invention in terms of examples set forthin some detail, it should be understood that these are by way ofillustration only and that the invention is not limited thereto.Alternative embodiments will become apparent to those skilled in the artin View or our description of the invention, and accordingly it iscontemplated that modifications may be made in the invention withoutdeparting from the spirit thereof.

What we claim is: v

l. An apparatus for determining vacuum equilibrium ash vaporization ofliquids which comprises means for flowing a liquid at -a selectedconstant rate, down-flow means for incompletely vaporizing the saidliquid under controlled temperature and pressure, bathed meanssubjacen-t to said downflow means for separating the evolved vapors,means for accumulating from said baffled means a standard volume ofunvaporized liquid under the selected conditions of temperature andpressure, and means for determining the time necessary to accumulatesaid standard volume as a measure of vacuum equilibrium flashvaporization.

2. A vacuum equilibrium flash vaporization apparatus which comprises incombination a constant volume flow feed pump, a downow flash equilibriumvaporizer, said vaporizer including an upper manifold section, a heatexchanger section consisting of a plurality of parallel channels, meansfor controlling the temperature of said vaporizer, a disengager sectionsubjacent to said heat exchanger section, said disengager sectionincluding a plurality of perforated cones arranged apex-to-apex andbase-toabase, a separator chamber, means for withdrawing vapor from saidvaporizer, an accumlator into which unvaporized feed -flows from saidseparator chamber, 'means for maintaining the 4apparatus at a desiredpressure, and means for timing the period within which the accumulatorcollects.

3. An apparatus for determining vacuum equilibrium flash vaporization ofliquids comprising vaporizer charnber means, downow heat exchanger meansin said vaporizer chamber means, vapor-liquid separator means in a lowerportion of said vaporizer, means for withdrawing vapor from saidvaporizer chamber, means for controlling the temperature of saidvaporizer, means for introducing sample liquid at a constant rate intoan upper portion of said vaporizer, means for withdrawing unvaporizedliquid from a lower portion of said vaporizer, accumulator meansaccumulating unvaporized liquid withdrawn from said vaporizer, saidaccumulator means including flask means, differential thermocouple meansextending within said flask means, and solenoid-operated valve meanscontrolling the outlet from said flask means, and vacuum pump means formaintaining subatomspheric pressure on said apparatus.

4. Vaporiz-er chamber means adapted for use in vacuum equilibrium flashvaporization tests which comprises a temperature-controlled block, arecess in one end of said block providing a manifold chamber, aplurality of parallel flow channels extending downwardly from saidmanifold chamber, an inlet to said manifold chamber, deflector meansinterposed said inlet and the top of said parallel channels, electricalmeans for controlling the temperature of the said block, an equilibriumchamber su-bjacent to said flow channels, outlet means from saidequilibrium chamber for withdrawing liquid therefrom, vapor outlet meansin an upper part of said equilibrium chamber, and a plurality ofperforated cones in an upper portion of said equilibrium chamber, onecone being arranged with its base across th-e lower end of saidchannels, a second cone arranged apexato-apex with the rst, and a third'arranged base-to-base with the second, said vapor outlet communicatingwith the space between said rst and second cones.

5. An equilibrium flas'h vaporization still comprising a verticallyelongated housing, a manifold chamber in the upper portion of saidhousing, a heat exchanger chamber in an intermediate portion of saidhousing, and an equilibrium chamber in a lower portion of said housing,an inlet at the top of said housing discharging into said manifoldchamber, deector means in said manifold chamber onto which the inletstream impinges, a plurality of parallel channels forming said heatexchanger chamber, a tirst perforated cone across the flow area of saidequilibrium chamber and having its base across the lower end of saidheat exchanger chamber, a second perforated cone similar to the firstand arranged apex-toapex with the first cone, and a third suchperforated cone arranged base-to-base with the second perforated cone,

liquid outlet means in the bottom of said housing, said outlet includinga weir over Whiclh unvaporized liquid ows, vapor outlet means from saidseparator chamber communicating with the space between said first andsecond perforated cones, electrical heating means in the walls of saidhousing, and thermocouple means extending through the walls of saidhousing -to a point below the upper edge of said Weir.

6. An apparatus for continuously determining the vacuum equilibriumflash vaporization characteristics of a high boiling hydrocarbon liquidwhich comprises in combination Aa downiow vapoxizer including a manifoldsection, a tubular Iheat exchange section and a liquidvapor separatorsection, means for maintaining said vaporizer at a constant temperature,means for providing controlled pressure in said vaporizer, means foraccumulating unvaporized liquid exterior of said vaporizer, outletconduit means for withdrawing vapors from said separator section, meansfor detecting the accumulation of a preselected volume of unvaporizedliquid in said accumulating means, electrical circuit means includingthermocouple means, a timer and a means for programming the ydischargeof the accumulated liquid from said accumulating means, means forcontrolling the heating of said vaporizer in response to the temperature.within the said separator section, and .vacuum pump means formaintaining said Vaporizer at the desired pressure via the said vaporoutlet conduit therefrom.

7. The apparatus of claim 1 which includes temperature responsive meansfor monitoring the liquid level in said accumulating means and means forprogramming the discharge of the accumulated liquid therefrom.

8. An apparatus for determining vaporization characteristics of liquidswhich comprises means for flowing a liquid at a selected constant rate,downow means for incompletely vaporizing the said liquid undercontrolled ,temperature and pressure, means s-ubjacent to said downflowmeans for separating evolved vapors, means for accumulating from saidsubjacent means a volume of unvaporized liquid under selected conditionsof temperature and pressure, means for sensing the temperature of theaccumulated liquid as a measure of its level, and means responsive tothe predetermined level measurement of said accumulated liquid foradjusting the temperature of the downow means.

9. A vaporization apparatus comprising in combination a constant volumeflow feed pump, a downflow vaporizer, said vaporizer including an uppermanifold section, a heat exchanger section consisting of a plurality ofparallel channels, means for controlling the temperature of saidvaporizer, a separator section subjacent to said heat exchanger section,said separator section including an accumulator into which unvaporizedfeed flows, means for withdrawing vapor from said accumulator, means formaintaining the apparatus at a desired pressure, and means responsive tothe temperature of the liquid in said accumulator, said last named meansactuating said means for controlling the temperature of said vaporizer.

References Cited in the file of this patent UNITED STATES PATENTS1,014,139 Freeman Jan. 9, 1912 2,002,101 Valby et al a May 2-1, 19352,122,762 Smith July 5, 1938 2,306,606 Hirsch Dec. 29, 1942 2,350,006Wolfner May 30, 1944

